March 2020 - Devel - libvirt List Archives

[libvirt PATCH 0/6] Introduce Local Migration Support in Libvirt
by Daniel P. Berrangé 03 Mar '20

03 Mar '20

I'm (re-)sending this patch series on behalf of Shaju Abraham <shaju.abraham(a)nutanix.com> who has tried to send this several times already. Red Hat's email infrastructure is broken, accepting the mails and then failing to deliver them to mailman, or any other Red Hat address. Unfortunately it means that while we can send comments back to Shaju on this thread, subscribers will then probably fail to see any responses Shaju tries to give :-( To say this is bad is an understatement. I have yet another ticket open tracking & escalating this awful problem but can't give any ETA on a fix :-( Anyway, with that out of the way, here's Shaju's original cover letter below.... 1) What is this patch series about? Local live migration of a VM is about Live migrating a VM instance with in the same node. Traditional libvirt live migration involves migrating the VM from a source node to a remote node. The local migrations are forbidden in Libvirt for a myriad of reasons. This patch series is to enable local migration in Libvirt. 2) Why Local Migration is important? The ability to Live migrate a VM locally paves the way for hypervisor upgrades without shutting down the VM. For example to upgrade qemu after a security upgrade, we can locally migrate the VM to the new qemu instance. By utilising capabilities like "bypass-shared-memory" in qemu, the hypervisor upgrades are faster. 3) Why is local migration difficult in Libvirt? Libvirt always assumes that the name/UUID pair is unique with in a node. During local migration there will be two different VMs with the same UUID/name pair which will confuse the management stack. There are other path variables like monitor path, config paths etc which assumes that the name/UUID pair is unique. So during migration the same monitor will be used by both the source and the target. We cannot assign a temporary UUID to the target VM, since UUID is a part of the machine ABI which is immutable. To decouple the dependecy on UUID/name, a new field (the domain id) is included in all the PATHs that Libvirt uses. This will ensure that all instances of the VM gets a unique PATH. 4) How is the Local Migration Designed ? Libvirt manages all the VM domain objects using two hash tables which are indexed using either the UUID or Name.During the Live migration the domain entry in the source node gets deleted and a new entry gets populated in the target node, which are indexed using the same name/UUID.But for the Local migration, there is no remote node. Both the source and the target nodes are same. So inorder to model the remote node, two more hashtables are introduced which represents the hash tables of the remote node during migration. The Libvirt migration involves 5 stages 1) Begin 2) Prepare 3) Perform 4) Finish 5) Confirm Begin,Perform and Confirm gets executed on the source node where as Prepare and Finish gets executed on the target node. In the case of Local Migration Perform and Finish stages uses the newly introduced 'remote hash table' and rest of the stages uses the 'source hash tables'. Once the migration is completed, that is after the confirm phase, the VM domain object is moved from the 'remote hash table' to the 'source hash table'. This is required so that other Libvirt commands like 'virsh list' can display all the VMs running in the node. 5) How to test Local Migration? A new flag 'local' is added to the 'virsh migrate' command to enable local migration. The syntax is virsh migrate --live --local 'domain-id' qemu+ssh://ip-address/system 6) What are the known issues? SeLinux policies is know to have issues with the creating /dev/hugepages entries during VM launch. In order to test local migration disable SeLinux using 'setenforce 0'. Shaju Abraham (6): Add VIR_MIGRATE_LOCAL flag to virsh migrate command Introduce remote hash tables and helper routines Add local migration support in QEMU Migration framework Modify close callback routines to handle local migration Make PATHs unique for a VM object instance Move the domain object from remote to source hash table include/libvirt/libvirt-domain.h | 6 + src/conf/virdomainobjlist.c | 232 +++++++++++++++++++++++++++++-- src/conf/virdomainobjlist.h | 10 ++ src/libvirt_private.syms | 4 + src/qemu/qemu_conf.c | 4 +- src/qemu/qemu_domain.c | 28 +++- src/qemu/qemu_domain.h | 2 + src/qemu/qemu_driver.c | 46 +++++- src/qemu/qemu_migration.c | 59 +++++--- src/qemu/qemu_migration.h | 5 + src/qemu/qemu_migration_cookie.c | 121 ++++++++-------- src/qemu/qemu_migration_cookie.h | 2 + src/qemu/qemu_process.c | 3 +- src/qemu/qemu_process.h | 2 + src/util/virclosecallbacks.c | 48 +++++-- src/util/virclosecallbacks.h | 3 + tools/virsh-domain.c | 7 + 17 files changed, 471 insertions(+), 111 deletions(-) -- 2.24.1

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[PATCH] rpc: 'getaddrinfo' function support both IPv4 and IPv6
by Zhimin Feng 02 Mar '20

02 Mar '20

If only IPv6 is configured and nscd is started, getaddrinfo function reture value is -9. So hints.ai_flags should include the AI_V4MAPPED flag. The following is the partial implementation of getaddrinfo(glibc): if (req->ai_family == AF_UNSPEC || req->ai_family == AF_INET) at->family = AF_INET; else if (req->ai_family == AF_INET6 && (req->ai_flags & AI_V4MAPPED)) { at->addr[3] = at->addr[0]; at->addr[2] = htonl (0xffff); at->addr[1] = 0; at->addr[0] = 0; at->family = AF_INET6; } else { result = -EAI_ADDRFAMILY; goto free_and_return; } Signed-off-by: Zhimin Feng <fengzhimin1(a)huawei.com> --- src/rpc/virnetsocket.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/rpc/virnetsocket.c b/src/rpc/virnetsocket.c index a217404fa6..c547acefc0 100644 --- a/src/rpc/virnetsocket.c +++ b/src/rpc/virnetsocket.c @@ -575,7 +575,7 @@ int virNetSocketNewConnectTCP(const char *nodename, memset(&hints, 0, sizeof(hints)); hints.ai_family = family; - hints.ai_flags = AI_PASSIVE | AI_ADDRCONFIG; + hints.ai_flags = AI_PASSIVE | AI_ADDRCONFIG | AI_V4MAPPED; hints.ai_socktype = SOCK_STREAM; int e = getaddrinfo(nodename, service, &hints, &ai); -- 2.19.1

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[PATCH] qemu: Don't compare local and remote hostnames on migration
by Michal Privoznik 02 Mar '20

02 Mar '20

Libvirt tries to forbid migration onto the same host and it does that by checking if local and remote hostnames are the same and whether local and remote UUIDs are the same. Well, the latter makes sense but the former doesn't really because libvirtd can be running inside an UTS namespace and hostnames can appear the same on both sides of migration. On the other hand, host UUIDs are unique, so rely on them when trying to prevent migration onto the same host. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1639596 Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com> --- src/qemu/qemu_migration_cookie.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/src/qemu/qemu_migration_cookie.c b/src/qemu/qemu_migration_cookie.c index a5a9edffc3..1d88ac1d22 100644 --- a/src/qemu/qemu_migration_cookie.c +++ b/src/qemu/qemu_migration_cookie.c @@ -1230,19 +1230,17 @@ qemuMigrationCookieXMLParse(qemuMigrationCookiePtr mig, } VIR_FREE(tmp); - /* Check & forbid "localhost" migration */ if (!(mig->remoteHostname = virXPathString("string(./hostname[1])", ctxt))) { virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("missing hostname element in migration data")); goto error; } - if (STREQ(mig->remoteHostname, mig->localHostname)) { - virReportError(VIR_ERR_INTERNAL_ERROR, - _("Attempt to migrate guest to the same host %s"), - mig->remoteHostname); - goto error; - } + /* Historically, this is the place where we checked whether remoteHostname + * and localHostname are the same. But even if they were, it doesn't mean + * the domain is migrating onto the same host. Rely on UUID which can tell + * for sure. */ + /* Check & forbid localhost migration */ if (!(tmp = virXPathString("string(./hostuuid[1])", ctxt))) { virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("missing hostuuid element in migration data")); -- 2.24.1

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[PATCH] admin: use g_autofree
by Gaurav Agrawal 02 Mar '20

02 Mar '20

Signed-off-by: Gaurav Agrawal <agrawalgaurav(a)gnome.org> --- src/admin/libvirt-admin.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/src/admin/libvirt-admin.c b/src/admin/libvirt-admin.c index 4099a54854..e272d7a422 100644 --- a/src/admin/libvirt-admin.c +++ b/src/admin/libvirt-admin.c @@ -111,7 +111,7 @@ getSocketPath(virURIPtr uri) virURIParamPtr param = &uri->params[i]; if (STREQ(param->name, "socket")) { - VIR_FREE(sock_path); + g_free(sock_path); sock_path = g_strdup(param->value); } else { virReportError(VIR_ERR_CONFIG_UNSUPPORTED, @@ -203,11 +203,11 @@ virAdmGetDefaultURI(virConfPtr conf, char **uristr) virAdmConnectPtr virAdmConnectOpen(const char *name, unsigned int flags) { - char *sock_path = NULL; + g_autofree char *sock_path = NULL; char *alias = NULL; virAdmConnectPtr conn = NULL; g_autoptr(virConf) conf = NULL; - char *uristr = NULL; + g_autofree char *uristr = NULL; if (virAdmInitialize() < 0) goto error; @@ -233,7 +233,7 @@ virAdmConnectOpen(const char *name, unsigned int flags) goto error; if (alias) { - VIR_FREE(uristr); + g_free(uristr); uristr = alias; } @@ -251,16 +251,11 @@ virAdmConnectOpen(const char *name, unsigned int flags) if (remoteAdminConnectOpen(conn, flags) < 0) goto error; - cleanup: - VIR_FREE(sock_path); - VIR_FREE(uristr); - return conn; error: virDispatchError(NULL); virObjectUnref(conn); - conn = NULL; - goto cleanup; + return NULL; } /** -- 2.24.1

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